fixed support for DATABASE_URL for rake db tasks

Backport for #7521

- added tests to confirm establish_connection uses DATABASE_URL and
  Rails.env correctly even when no arguments are passed in.
- updated rake db tasks to support DATABASE_URL, and added tests to
  confirm correct behavior for these rake tasks.  (Removed
  establish_connection call from some tasks since in those cases
  the :environment task already made sure the function would be called)
- updated Resolver so that when it resolves the database url, it
  removes hash values with empty strings from the config spec (e.g.
  to support connection to postgresql when no username is specified).
- updated ResolverTest to use current_adapter? to check the type of
  the current adapter.

2 files changed, 55 insertions, 35 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb b/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb
index f366392c50..04ab7e0a43 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb
@@ -67,7 +67,7 @@ module ActiveRecord
                    :port     => config.port,
                    :database => config.path.sub(%r{^/},""),
                    :host     => config.host }
-          spec.reject!{ |_,value| !value }
+          spec.reject!{ |_,value| value.blank? }
           spec.map { |key,value| spec[key] = URI.unescape(value) if value.is_a?(String) }
           if config.query
             options = Hash[config.query.split("&").map{ |pair| pair.split("=") }].symbolize_keys
diff --git a/activerecord/lib/active_record/railties/databases.rake b/activerecord/lib/active_record/railties/databases.rake
index 987bb558e5..ae6d9c8653 100644
--- a/activerecord/lib/active_record/railties/databases.rake
+++ b/activerecord/lib/active_record/railties/databases.rake
@@ -2,6 +2,25 @@ require 'active_support/core_ext/object/inclusion'
 require 'active_record'
 
 db_namespace = namespace :db do
+  def database_url_config
+    @database_url_config ||=
+        ActiveRecord::Base::ConnectionSpecification::Resolver.new(ENV["DATABASE_URL"], {}).spec.config.stringify_keys
+  end
+
+  def current_config(options = {})
+    options = { :env => Rails.env }.merge! options
+
+    if options[:config]
+      @current_config = options[:config]
+    else
+      @current_config ||= if ENV['DATABASE_URL']
+                            database_url_config
+                          else
+                            ActiveRecord::Base.configurations[options[:env]]
+                          end
+    end
+  end
+
   task :load_config do
     ActiveRecord::Base.configurations = Rails.application.config.database_configuration
     ActiveRecord::Migrator.migrations_paths = Rails.application.paths['db/migrate'].to_a
@@ -35,10 +54,14 @@ db_namespace = namespace :db do
     end
   end
 
-  desc 'Create the database from config/database.yml for the current Rails.env (use db:create:all to create all dbs in the config)'
+  desc 'Create the database from DATABASE_URL or config/database.yml for the current Rails.env (use db:create:all to create all dbs in the config)'
   task :create => [:load_config, :rails_env] do
-    configs_for_environment.each { |config| create_database(config) }
-    ActiveRecord::Base.establish_connection(configs_for_environment.first)
+    if ENV['DATABASE_URL']
+      create_database(database_url_config)
+    else
+      configs_for_environment.each { |config| create_database(config) }
+      ActiveRecord::Base.establish_connection(configs_for_environment.first)
+    end
   end
 
   def mysql_creation_options(config)
@@ -133,9 +156,13 @@ db_namespace = namespace :db do
     end
   end
 
-  desc 'Drops the database for the current Rails.env (use db:drop:all to drop all databases)'
+  desc 'Drops the database using DATABASE_URL or the current Rails.env (use db:drop:all to drop all databases)'
   task :drop => [:load_config, :rails_env] do
-    configs_for_environment.each { |config| drop_database_and_rescue(config) }
+    if ENV['DATABASE_URL']
+      drop_database_and_rescue(database_url_config)
+    else
+      configs_for_environment.each { |config| drop_database_and_rescue(config) }
+    end
   end
 
   def local_database?(config, &block)
@@ -146,7 +173,6 @@ db_namespace = namespace :db do
     end
   end
 
-
   desc "Migrate the database (options: VERSION=x, VERBOSE=false)."
   task :migrate => [:environment, :load_config] do
     ActiveRecord::Migration.verbose = ENV["VERBOSE"] ? ENV["VERBOSE"] == "true" : true
@@ -201,8 +227,6 @@ db_namespace = namespace :db do
 
     desc 'Display status of migrations'
     task :status => [:environment, :load_config] do
-      config = ActiveRecord::Base.configurations[Rails.env]
-      ActiveRecord::Base.establish_connection(config)
       unless ActiveRecord::Base.connection.table_exists?(ActiveRecord::Migrator.schema_migrations_table_name)
         puts 'Schema migrations table does not exist yet.'
         next  # means "return" for rake task
@@ -222,7 +246,7 @@ db_namespace = namespace :db do
         ['up', version, '********** NO FILE **********']
       end
       # output
-      puts "\ndatabase: #{config['database']}\n\n"
+      puts "\ndatabase: #{ActiveRecord::Base.connection_config[:database]}\n\n"
       puts "#{'Status'.center(8)}  #{'Migration ID'.ljust(14)}  Migration Name"
       puts "-" * 50
       (db_list + file_list).sort_by {|migration| migration[1]}.each do |migration|
@@ -314,7 +338,6 @@ db_namespace = namespace :db do
     task :load => [:environment, :load_config] do
       require 'active_record/fixtures'
 
-      ActiveRecord::Base.establish_connection(Rails.env)
       base_dir     = File.join [Rails.root, ENV['FIXTURES_PATH'] || %w{test fixtures}].flatten
       fixtures_dir = File.join [base_dir, ENV['FIXTURES_DIR']].compact
 
@@ -353,7 +376,6 @@ db_namespace = namespace :db do
       require 'active_record/schema_dumper'
       filename = ENV['SCHEMA'] || "#{Rails.root}/db/schema.rb"
       File.open(filename, "w:utf-8") do |file|
-        ActiveRecord::Base.establish_connection(Rails.env)
         ActiveRecord::SchemaDumper.dump(ActiveRecord::Base.connection, file)
       end
       db_namespace['schema:dump'].reenable
@@ -377,25 +399,25 @@ db_namespace = namespace :db do
   namespace :structure do
     desc 'Dump the database structure to db/structure.sql. Specify another file with DB_STRUCTURE=db/my_structure.sql'
     task :dump => [:environment, :load_config] do
-      abcs = ActiveRecord::Base.configurations
+      config = current_config
       filename = ENV['DB_STRUCTURE'] || File.join(Rails.root, "db", "structure.sql")
-      case abcs[Rails.env]['adapter']
+      case config['adapter']
       when /mysql/, 'oci', 'oracle'
-        ActiveRecord::Base.establish_connection(abcs[Rails.env])
+        ActiveRecord::Base.establish_connection(config)
         File.open(filename, "w:utf-8") { |f| f << ActiveRecord::Base.connection.structure_dump }
       when /postgresql/
-        set_psql_env(abcs[Rails.env])
-        search_path = abcs[Rails.env]['schema_search_path']
+        set_psql_env(config)
+        search_path = config['schema_search_path']
         unless search_path.blank?
           search_path = search_path.split(",").map{|search_path_part| "--schema=#{Shellwords.escape(search_path_part.strip)}" }.join(" ")
         end
-        `pg_dump -i -s -x -O -f #{Shellwords.escape(filename)} #{search_path} #{Shellwords.escape(abcs[Rails.env]['database'])}`
+        `pg_dump -i -s -x -O -f #{Shellwords.escape(filename)} #{search_path} #{Shellwords.escape(config['database'])}`
         raise 'Error dumping database' if $?.exitstatus == 1
       when /sqlite/
-        dbfile = abcs[Rails.env]['database']
+        dbfile = config['database']
         `sqlite3 #{dbfile} .schema > #{filename}`
       when 'sqlserver'
-        `smoscript -s #{abcs[Rails.env]['host']} -d #{abcs[Rails.env]['database']} -u #{abcs[Rails.env]['username']} -p #{abcs[Rails.env]['password']} -f #{filename} -A -U`
+        `smoscript -s #{config['host']} -d #{config['database']} -u #{config['username']} -p #{config['password']} -f #{filename} -A -U`
       when "firebird"
         set_firebird_env(abcs[Rails.env])
         db_string = firebird_db_string(abcs[Rails.env])
@@ -412,36 +434,34 @@ db_namespace = namespace :db do
 
     # desc "Recreate the databases from the structure.sql file"
     task :load => [:environment, :load_config] do
-      env = Rails.env
-
-      abcs = ActiveRecord::Base.configurations
+      config = current_config
       filename = ENV['DB_STRUCTURE'] || File.join(Rails.root, "db", "structure.sql")
-      case abcs[env]['adapter']
+      case config['adapter']
       when /mysql/
-        ActiveRecord::Base.establish_connection(abcs[env])
+        ActiveRecord::Base.establish_connection(config)
         ActiveRecord::Base.connection.execute('SET foreign_key_checks = 0')
         IO.read(filename).split("\n\n").each do |table|
           ActiveRecord::Base.connection.execute(table)
         end
       when /postgresql/
-        set_psql_env(abcs[env])
-        `psql -f "#{filename}" #{abcs[env]['database']}`
+        set_psql_env(config)
+        `psql -f "#{filename}" #{config['database']}`
       when /sqlite/
-        dbfile = abcs[env]['database']
+        dbfile = config['database']
         `sqlite3 #{dbfile} < "#{filename}"`
       when 'sqlserver'
-        `sqlcmd -S #{abcs[env]['host']} -d #{abcs[env]['database']} -U #{abcs[env]['username']} -P #{abcs[env]['password']} -i #{filename}`
+        `sqlcmd -S #{config['host']} -d #{config['database']} -U #{config['username']} -P #{config['password']} -i #{filename}`
       when 'oci', 'oracle'
-        ActiveRecord::Base.establish_connection(abcs[env])
+        ActiveRecord::Base.establish_connection(config)
         IO.read(filename).split(";\n\n").each do |ddl|
           ActiveRecord::Base.connection.execute(ddl)
         end
       when 'firebird'
-        set_firebird_env(abcs[env])
-        db_string = firebird_db_string(abcs[env])
+        set_firebird_env(config)
+        db_string = firebird_db_string(config)
         sh "isql -i #{filename} #{db_string}"
       else
-        raise "Task not supported by '#{abcs[env]['adapter']}'"
+        raise "Task not supported by '#{config['adapter']}'"
       end
     end
 
@@ -465,10 +485,10 @@ db_namespace = namespace :db do
     # desc "Recreate the test database from an existent structure.sql file"
     task :load_structure => 'db:test:purge' do
       begin
-        old_env, ENV['RAILS_ENV'] = ENV['RAILS_ENV'], 'test'
+        current_config(:config => ActiveRecord::Base.configurations['test'])
         db_namespace["structure:load"].invoke
       ensure
-        ENV['RAILS_ENV'] = old_env
+        current_config(:config => nil)
       end
     end